Electroactive polymer actuator with improved performance

Abstract

An electroactive polymer transducer including a dielectric elastomer material having a first configuration with a first spring constant and a second configuration with a second spring constant and where the second spring constant is lower than the first spring constant.

What is claimed is: 
     
         1 . An aircraft starting and generating system, comprising:
 a starter/generator that includes a main machine, an exciter, and a permanent magnet generator;   a direct current (DC) power output from the starter/generator;   a load-leveling unit (LLU) selectively coupled with the DC power output and having an inverter/converter/controller (ICC) having a LLU metal oxide semiconductor field effect transistor (MOSFET)-based bridge configuration and that supplies DC power to the DC power output in a supply mode, and that receives DC power from the DC power output, in a receive mode; and   a LLU bridge gate driver configured to drive the LLU MOSFET-based bridge;   wherein the LLU bridge gate driver operates to drive the LLU MOSFET-based bridge during supply mode and receive mode using bi-polar pulse width modulation (PWM).   
     
     
         2 . The aircraft starting and generating system of  claim 1  wherein the LLU further comprises a power storage device. 
     
     
         3 . The aircraft starting and generating system of  claim 2  wherein the power storage device comprises at least one of a battery, a fuel cell, or an ultracapacitor. 
     
     
         4 . The aircraft starting and generating system of  claim 2  wherein the power storage device is configured to discharge power to the ICC during the supply mode and absorb power from the ICC during the receive mode. 
     
     
         5 . The aircraft starting and generating system of  claim 3  wherein the power storage device is configured to discharge power simultaneously and in parallel with the starter/generator during periods of peak power requirements. 
     
     
         6 . The aircraft starting and generating system of  claim 1  wherein the LLU MOSFET-based bridge further comprises at least one of a silicon carbide-based bridge or Gallium Nitride-based bridge. 
     
     
         7 . The aircraft starting and generating system of  claim 1 , further comprising a main machine MOSFET-based bridge that is connected to a stator of the main machine, and a main machine bridge gate driver configured to drive the main machine MOSFET-based bridge. 
     
     
         8 . The aircraft starting and generating system of  claim 7  wherein the main machine comprises a main machine MOSFET-based bridge configuration that absorbs excess power of the system in a regeneration mode by storing the excess power in the kinetic energy of the prime mover of the aircraft, and wherein the main machine bridge gate driver operates to drive the main machine MOSFET-based bridge during regeneration mode using Space Vector Pulse Width Modulation. 
     
     
         9 . The aircraft starting and generating system of  claim 8  wherein the main machine MOSFET-based bridge further comprises at least one of a silicon carbide-based bridge or Gallium Nitride-based bridge. 
     
     
         10 . The aircraft starting and generating system of  claim 1  wherein the LLU MOSFET-based bridge further comprises an array of individually-controllable MOSFETs. 
     
     
         11 . The aircraft starting and generating system of  claim 10  wherein the LLU bridge gate driver operates to drive each individually-controllable MOSFET. 
     
     
         12 . The aircraft starting and generating system of  claim 1  wherein the LLU MOSFET-based bridge further comprises individually-controllable wide bandgap device MOSFETs. 
     
     
         13 . The aircraft starting and generating system of  claim 12  wherein the MOSFETs further comprise external diodes configured across a body diode of the MOSFETs. 
     
     
         14 . A method of controlling an aircraft starting and generating system having a starter/generator that includes a main machine having a DC power output, an exciter, and a permanent magnet generator, a load leveling unit (LLU) selectively coupled with the DC power output and having an inverter/converter/controller (ICC) having a MOSFET-based bridge configuration, and a LLU bridge gate driver configured to drive the MOSFET-based bridge, the method comprising:
 if in supply mode, selectively coupling the DC power output with the MOSFET-based bridge and supplying power to the DC power output from the MOSFET-based bridge by driving the MOSFET-based bridge during supply mode using bi-polar Pulse Width Modulation (PWM); and   if in receive mode, selectively coupling the DC power output with the MOSFET-based bridge and receiving power from the DC power output to the MOSFET-based bridge by driving the MOSFET-based bridge using bi-polar PWM.   
     
     
         15 . The method of  claim 14  wherein, if in supply mode, the supplying power from the MOSFET-based bridge further comprises supplying power from a power storage device to the MOSFET-based bridge. 
     
     
         16 . The method of  claim 15  wherein supplying power from a power storage device further comprises discharging at least a portion of at least one of a battery, a fuel cell, or an ultracapacitor. 
     
     
         17 . The method of  claim 14 , further comprising, if in start mode, selectively coupling the DC power output with the MOSFET-based bridge and supplying power from the MOSFET-based bridge and driving the MOSFET-based bridge during start mode using bi-polar PWM, and wherein the driving the main MOSFET-based bridge during start mode starts a prime mover of the aircraft. 
     
     
         18 . The method of  claim 17  wherein the supplying power from the MOSFET-based bridge further comprises supplying power from a power storage device to the MOSFET-based bridge. 
     
     
         19 . The method of  claim 14 , further comprising selectively switching between supply mode and receive mode. 
     
     
         20 . An aircraft comprising:
 an engine;   a starter/generator connected to the engine, and having a main machine, an exciter, and a permanent magnet generator;   a direct current (DC) power output from the starter/generator;   a load-leveling unit (LLU) selectively coupled with the DC power output and having an inverter/converter/controller (ICC) with a LLU metal oxide semiconductor field effect transistor (MOSFET)-based bridge configuration and that supplies DC power to the DC power output in a supply mode, and that receives DC power from the DC power output, in a receive mode; and   a LLU bridge gate driver configured to drive the LLU MOSFET-based bridge;   wherein the LLU bridge gate driver operates to drive the LLU MOSFET-based bridge during a supply mode and a receive mode using bi-polar pulse width modulation (PWM).